•Back to equilibrium expression

•

•               [(RSO3-)x Mx+]s [H+]xaq

•   Kex  =  -----------------------------

•                [RSO3- H+]xs [Mx+]xaq   

•Rearrange to

•

•  [RSO3- H+]xs                       [(RSO3-)x Mx+]s

• ------------------   Kex  =  ---------------------

•       [H+]xaq                            [Mx+]xaq

•

•During elution [H+] is high & [RSO3- H+]s is high

•Left hand side of equation essentially constant